Polyploidy and novelty: Gottlieb's legacy

Abstract

Nearly four decades ago, Roose & Gottlieb (Roose & Gottlieb 1976 Evolution 30 , 818–830. ( doi:10.2307/2407821 )) showed that the recently derived allotetraploids Tragopogon mirus and T. miscellus combined the allozyme profiles of their diploid parents ( T. dubius and T. porrifolius , and T. dubius and T. pratensis , respectively). This classic paper addressed the link between genotype and biochemical phenotype and documented enzyme additivity in allopolyploids. Perhaps more important than their model of additivity, however, was their demonstration of novelty at the biochemical level. Enzyme multiplicity—the production of novel enzyme forms in the allopolyploids—can provide an extensive array of polymorphism for a polyploid individual and may explain, for example, the expanded ranges of polyploids relative to their diploid progenitors. In this paper, we extend the concept of evolutionary novelty in allopolyploids to a range of genetic and ecological features. We observe that the dynamic nature of polyploid genomes—with alterations in gene content, gene number, gene arrangement, gene expression and transposon activity—may generate sufficient novelty that every individual in a polyploid population or species may be unique. Whereas certain combinations of these features will undoubtedly be maladaptive, some unique combinations of newly generated variation may provide tremendous evolutionary potential and adaptive capabilities.

Patterns of chromosomal variation in natural populations of the neoallotetraploid Tragopogon mirus (Asteraceae)

“…The finding that all populations show heterogeneity in chromosome composition reflects an inability of natural selection to eliminate meiotically unstable lineages over the timeframe since the allopolyploids formed. This prolonged window of instability opens up possibilities for alterations and the generation of karyotypic novelty in neoallopolyploids, for example, see Soltis et al (2014).…”

A Time-Calibrated Road Map of Brassicaceae Species Radiation and Evolutionary History

“…Consequently, all angiosperm lineages can be considered polyploid (Amborella Genome Project, 2013), and many of them have undergone multiple WGD events. However, major questions concerning polyploid evolution have been discussed since Stebbins (1938Stebbins ( , 1950 (reviewed in Soltis et al, 2014), and there is ongoing discussion about the importance of polyploidization for plant species diversification (Mayrose et al, 2011;Arrigo and Barker, 2012;Soltis et al, 2014). Do polyploids have an advantage over their diploid ancestors, and how is this realized?…”

The legacy of diploid progenitors in allopolyploid gene expression patterns

“…Gottlieb ([2], p. 91) A common phenomenon in plant evolution is the hybridization of two diploid species, accompanied by whole-genome duplication, to produce an allotetraploid species with two homoeologous sub-genomes (see contributions by Soltis et al [3], Ramsey & Ramsey [4], Vanneste et al [5], Jiao & Paterson [6]). New allotetraploids contain duplicate copies of every gene that was present in both their parents.…”